Samoans will have to start paying a hefty fee to fly on Samoa Air if they're overweight.

Samoa Air is the first airline to make customers pay as much as they weigh when flying on the airline. For overweight customers, this could mean big charges.

"This is the fairest way of travelling," said Chris Langton, chief executive of Samoa Air. "There are no extra fees in terms of excess baggage or anything – it is just a kilo is a kilo is a kilo."

Customers will have to start typing in their weight when purchasing Samoa Air tickets online, and pay anywhere from about $1 to about $4.16 per kilogram (depending on whether they're traveling short domestic routes or between Samoa and American Samoa).

Once arriving at the airport, the customers are weighed again to make sure they didn't lie online.

Why is Samoa Air doing this? According to Langton, it's partially meant to raise awareness of obesity and health, since Samoa is often in the top 10 lists for obesity.

"When you get into the Pacific, standard weight is substantially higher [than south-east Asia]," said Langton. "That's a health issue in some areas. [This payment system] has raised the awareness of weight."

The payment by weight system will have other benefits, such as safety measures where a plane can only handle so many overweight customers (larger passengers have to be evenly distributed on the plane for safety); families with young children could pay much less than what they're paying now, and carriers could gain the money lost on fuel for carrying heavier passengers.

quote: Looking at the Boeing 767-400, operating empty weight is 229,000lbs and max take off weight is 450,000lbs giving about 220,000lbs of cargo and passenger weight.So the actual percentage increase in fuel costs if you double passenger weight, assuming fuel costs are linear with weight ( it isn't, 1% reduction in weight only gets you a 0.75% reduction in fuel use), is ((450,000/(229,000+110,000))-1)*100= 33%.

You're distributing the cost of the plane's weight on a per person basis. That's arguably the wrong way to do it.

Say I put two pallets aboard a cargo plane. One is a tank weighing 70 tons. The other is an overnight envelope. After you subtract out the cost of the fuel needed to fly the weight of the cargo, are you seriously going to suggest that half of the cost to fly the plane itself should be attributed to the envelope, and half to the tank?

It makes more sense to distribute the cost of the plane's weight on a per pound of payload basis. Your 767 has a maximum payload of 220,000. The 300 pound person consumes 0.136% of that. The 150 pound person takes 0.068% of that. And they should pay accordingly.

quote: It makes more sense to distribute the cost of the plane's weight on a per pound of payload basis. Your 767 has a maximum payload of 220,000. The 300 pound person consumes 0.136% of that. The 150 pound person takes 0.068% of that. And they should pay accordingly.

That fraction covers the cost of the cargo/person, but then who pays for the fuel it costs to actually lift the plane itself?

To be perfectly fair and cover operating costs there needs to be a base price with a weight modifier. Totally fictional numbers here for an example: say it costs $5,000 to operate the flight if it were void of any passengers or luggage. If it will carry 100 passengers then the base price will be $50 per passenger. Then to cover any fuel costs over that of the empty plane plus crew figure what that is per pound and charge every passenger that charge per pound for them and their luggage. If a ten year old weighs 60 pounds and has no luggage and an adult weighs 180 pounds and has 60 pounds of luggage then their surcharge is four times that of the child's. Add the weight surcharge to the base and you have the price of the ticket. That is the fair way to do it.

Currently if you say that anyone over 300 pounds must pay a surcharge then that means that anyone at 299-300 pounds is getting the best bang for their buck on ticket price, while a 90 pound girl is getting a terrible deal as she is paying much more per pound for her ticket.